According to the insulating medium, the distribution transformer can be divided into a transformer of oil, gas filled transformers and transformer of silicon. It can also be divided into sealed transformers, geoelectric transformers, winding transformers, and so on according to the types from structure. The key lies in the performance and index. We also need to consider the location that is used to suit the local conditions and meet the operation requirements. The development goal of distribution transformer is low loss, especially low open circuit losses, and highlight the effect of energy saving. It needs the characteristics of low noise, especially the carrying idler noise, and meets the environmental protection requirements. It is fully sealed to make the transformer oil not contact with the outside air to meet the maintenance of free requirements. The protection device is loaded into the tank and miniaturized; it reduces the size of the distribution transformer and is convenient for the installation of the field. It does not have charge when it is exposed to the air and it is safe to use. It has the characteristics of small size, light weight, reliable operation and convenient maintenance.